Evaluation of blaOXA-48-like point mutation carbapenemase-producing Enterobacterales in Prapokklao Hospital, Thailand

Abstract

Carbapenemase-producing Enterobacterales (CPE) isolates increasingly carry oxacillinase-48 (OXA-48)-like enzymes encoded by blaOXA-48-like, which can confer high levels of carbapenem resistance. This aims to determine the prevalence of CPE and genetic variation among blaOXA-48-like-carrying isolates recovered from Prapokklao Hospital in Chanthaburi Province, Thailand in 2016-2017. In total, 122 carbapenem-resistant Enterobacterales (CRE) isolates were recovered from clinical samples. CRE were evaluated using standard biochemical tests and MIC test strips. Carbapenemase production was assessed through the modifiedHodge test (MHT), modifiedcarbapenem inactivation method (mCIM), and EDTA-modifiedcarbapenem inactivation method (eCIM). Detection of blaOXA-48-like mutations was conducted via PCR and confirmedby Sanger sequencing. Among these CRE isolates, 72 (59.02%), 44 (36.07%), 3 (2.46%), and 3 (2.46%) were Klebsiella pneumoniae, Escherichia coli, Enterobacter aerogenes, and Enterobacter cloacae, respectively. The MHT identifiedcarbapenemase production in 108 isolates (88.52%). Based on the mCIM, 81 isolates (66.39%) were carbapenemase producers. Seventy-three isolates (59.84%) were eCIM-positive, indicating metallo-β-lactamase production. Three distinct genetic variants of the blaOXA-48-like gene were identifiedamong the isolates, including the wild-type and two point mutation types harboring the mutations E168Q and S171A (mutation type 1) and E168Q, S171A, and R214S (mutation type 2). Multiple-sequence alignment and in silico analysis revealed variation of R214 located in the β5-β6 loop. This study identifiedblaOXA-48-like point mutation groups and carbapenemase production, predominantly metallo-β-lactamases, among CRE isolates, especially K. pneumoniae and E. coli. These findingshighlight the importance of implementing stringent infection control measures and active antimicrobial resistance surveillance to combat the spread of difficult-to-treat,metallo-β-lactamase-producing CRE in healthcare settings.